Design-Oriented Analysis of Slow-Scale Bifurcations in Single Phase DC–AC Inverters via Autonomous Transformation Approach

2017 ◽  
Vol 27 (06) ◽  
pp. 1750086 ◽  
Author(s):  
Hao Zhang ◽  
Honghui Ding ◽  
Chuanzhi Yi
Keyword(s):  
Theoretical Analysis ◽  
Circuit Design ◽  
Single Phase ◽  
Underlying Mechanism ◽  
System Stability ◽  
Equivalent Model ◽  
Eigenvalue Sensitivity ◽  
Physical Experiments ◽  
Averaged Model ◽  
Theoretical Results

This paper deals with the design-oriented analysis of slow-scale bifurcations in single phase DC–AC inverters. Since DC–AC inverter belongs to a class of nonautonomous piecewise systems with periodic equilibrium orbits, the original averaged model has to be translated into an equivalent autonomous one via a virtual rotating coordinate transformation in order to simplify the theoretical analysis. Based on the virtual equivalent model, eigenvalue sensitivity is used to estimate the effect of the important parameters on the system stability. Furthermore, theoretical analysis is performed to identify slow-scale bifurcation behaviors by judging in what way the eigenvalue loci of the Jacobian matrix move under the variation of some important parameters. In particular, the underlying mechanism of the slow-scale unstable phenomenon is uncovered and discussed thoroughly. In addition, some behavior boundaries are given in the parameter space, which are suitable for optimizing the circuit design. Finally, physical experiments are performed to verify the above theoretical results.

Observer-Pattern Modeling and Slow-Scale Bifurcation Analysis of Two-Stage Boost Inverters

2017 ◽  
Vol 27 (06) ◽  
pp. 1750096 ◽  
Author(s):  
Hao Zhang ◽  
Xiaojin Wan ◽  
Weijie Li ◽  
Honghui Ding ◽  
Chuanzhi Yi
Keyword(s):  
Bifurcation Analysis ◽  
Second Harmonic ◽  
Underlying Mechanism ◽  
Analysis Method ◽  
Two Stage ◽  
Time Variance ◽  
Eigenvalue Sensitivity ◽  
Averaged Equations ◽  
Pattern Modeling ◽  
Theoretical Results

This paper deals with modeling and bifurcation analysis of two-stage Boost inverters. Since the effect of the nonlinear interactions between source-stage converter and load-stage inverter causes the “hidden” second-harmonic current at the input of the downstream H-bridge inverter, an observer-pattern modeling method is proposed by removing time variance originating from both fundamental frequency and hidden second harmonics in the derived averaged equations. Based on the proposed observer-pattern model, the underlying mechanism of slow-scale instability behavior is uncovered with the help of eigenvalue analysis method. Then eigenvalue sensitivity analysis is used to select some key system parameters of two-stage Boost inverter, and some behavior boundaries are given to provide some design-oriented information for optimizing the circuit. Finally, these theoretical results are verified by numerical simulations and circuit experiment.

Intermediate-Frequency Oscillation Behavior of One-Cycle Controlled SEPIC Power Factor Correction Converter via Floquet Multiplier Sensitivity Analysis

2016 ◽  
Vol 26 (10) ◽  
pp. 1650163 ◽  
Author(s):  
Hao Zhang ◽  
Shuai Dong ◽  
Yuan Zhang ◽  
Bo He
Keyword(s):  
Power Factor ◽  
Power Factor Correction ◽  
Monodromy Matrix ◽  
Intermediate Frequency ◽  
Underlying Mechanism ◽  
System Stability ◽  
Floquet Multiplier ◽  
Frequency Oscillation ◽  
The Stability ◽  
Averaged Model

In this paper, we investigate the intermediate-frequency oscillation in a SEPIC power-factor-correction (PFC) converter under one-cycle control. The converter operates in continuous conduction mode (CCM). A systematic method is proposed to analyze the bifurcation behavior and explain the inherent physical mechanism of the intermediate-frequency oscillation. Based on the nonlinear averaged model, the approximate analytical expressions of the nominal periodic equilibrium state are calculated with the help of Galerkin approach. Then, the stability of the system is judged by the Floquet theory and the Floquet multiplier movement of the monodromy matrix is analyzed to reveal the underlying mechanism of the intermediate-frequency oscillation behavior. In addition, Floquet multiplier sensitivity is proposed to facilitate the selection of key parameters with respect to system stability so as to guide the optimal design of the system. Finally, PSpice circuit experiments are performed to verify the above theoretical and numerical ones.

scholarly journals Optimising the AR Engraved Structure on Light-Guide Facets for a Wide Range of Wavelengths

Optics ◽  
2020 ◽  
Vol 2 (1) ◽  
pp. 25-42
Author(s):  
Ioseph Gurwich ◽  
Yakov Greenberg ◽  
Kobi Harush ◽  
Yarden Tzabari
Keyword(s):  
Theoretical Analysis ◽  
Light Guide ◽  
Spectral Band ◽  
Angular Range ◽  
The Past ◽  
Input And Output ◽  
Wide Range ◽  
The Given ◽  
Theoretical Results ◽  
Shape And Size

The present study is aimed at designing anti-reflective (AR) engraving on the input–output surfaces of a rectangular light-guide. We estimate AR efficiency, by the transmittance level in the angular range, determined by the light-guide. Using nano-engraving, we achieve a uniform high transmission over a wide range of wavelengths. In the past, we used smoothed conical pins or indentations on the faces of light-guide crystal as the engraved structure. Here, we widen the class of pins under consideration, following the physical model developed in the previous paper. We analyze the smoothed pyramidal pins with different base shapes. The possible effect of randomization of the pins parameters is also examined. The results obtained demonstrate optimized engraved structure with parameters depending on the required spectral range and facet format. The predicted level of transmittance is close to 99%, and its flatness (estimated by the standard deviation) in the required wavelengths range is 0.2%. The theoretical analysis and numerical calculations indicate that the obtained results demonstrate the best transmission (reflection) we can expect for a facet with the given shape and size for the required spectral band. The approach is equally useful for any other form and of the facet. We also discuss a simple way of comparing experimental and theoretical results for a light-guide with the designed input and output features. In this study, as well as in our previous work, we restrict ourselves to rectangular facets. We also consider the limitations on maximal transmission produced by the size and shape of the light-guide facets. The theoretical analysis is performed for an infinite structure and serves as an upper bound on the transmittance for smaller-size apertures.

The theoretical analysis and simulation of acoustic absorber for nonlinear shunted loudspeaker

2021 ◽  
Vol 263 (6) ◽  
pp. 388-393
Author(s):  
Wenjiang Wang ◽  
Xianhui Li ◽  
Junjuan Zhao ◽  
Peng Zhang ◽  
Xinyun Li ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Sound Absorption ◽  
Nonlinear Term ◽  
Equivalent Model ◽  
Frequency Bandwidth ◽  
Nonlinear Circuit ◽  
Van Der Pol ◽  
Absorption Bandwidth ◽  
Simulation Results ◽  
Different Time Scales

In this paper, a nonlinear electroacoustic absorber based on a tunable loudspeaker is proposed to broaden its sound absorption bandwidth. The main mechanism is a nonlinear circuit is coupled at loudspeaker's terminal. A series of theoretical analysis and simulation work are carried out in this paper. The equivalent model is composed of a linear term describing the loudspeaker and a nonlinear term of a coupled Duffing-van Der Pol bistable circuit. The invariant manifold method is used to solve different time scales. The analysis and simulation results show that the nonlinear circuit can widen the frequency bandwidth of the structure.

scholarly journals Research of transient processes in case of single-phase insulation faults in low-voltage ship power grids, taking into account the resistance at the fault point

2020 ◽  
pp. 49-54
Author(s):  
И.Е. Кажекин
Keyword(s):  
Single Phase ◽  
Low Voltage ◽  
Experimental Studies ◽  
Power Grids ◽  
Transient Processes ◽  
Safety Issues ◽  
Physical Experiments ◽  
Marine Industry ◽  
Calculation Results ◽  
Constant Potential

В работе рассмотрены вопросы безопасности бортовых электросетей объектов морской индустрии, показано влияние перенапряжений на их основные показатели, которыми определяются опасности смертельных электротравм, опасности возникновения пожаров и взрывов. Представлены результаты математического моделирования электрического разряда по уравнению Майра с учетом особенностей переходного процесса при однофазных замыканиях на корпус. Показана роль напряжения смещения нейтрали по постоянному потенциалу, наибольшие значения которого формируются при неустойчивом контакте фазы с корпусом судна. Описаны результаты экспериментальных исследований переходных процессов, сопровождающихся возникновением неустойчивыми искровыми разрядами. Сравнение результатов расчета по предложенной методике с результатами физических экспериментов показало весьма удовлетворительную сходимость. Предложенная модель может быть использована для уточнения показателей, характеризующих безопасность судовых электросетей. The paper deals with the safety issues of on-board power grids of the marine industry facilities, shows the influence of overvoltages on their main indicators, which determine the dangers of fatal electrical injuries, the risk of fires and explosions. The results of mathematical modeling of an electric discharge according to the Mayr equation, taking into account the features of the transient process in single-phase short circuits to the case, are presented. The role of the bias voltage of the neutral at a constant potential is shown, the highest values ​​of which are formed during unstable contact of the phase with the ship's hull. The results of experimental studies of transient processes accompanied by the appearance of unstable spark discharges are described. Comparison of the calculation results by the proposed method with the results of physical experiments showed a very satisfactory convergence. The proposed model can be used to refine the indicators characterizing the safety of ship power grids.

scholarly journals Multi-machine transient stability by using static synchronous series compensator

2020 ◽  
Vol 11 (3) ◽  
pp. 1249
Author(s):  
Nur Ashida Salim ◽  
Nur Diyana Shahirah Mohd Zain ◽  
Hasmaini Mohamad ◽  
Zuhaila Mat Yasin ◽  
Nur Fadilah Ab Aziz
Keyword(s):  
Power System ◽  
Transient Stability ◽  
Single Phase ◽  
Power Transmission ◽  
System Stability ◽  
Phase System ◽  
Proportional Integral ◽  
Before And After ◽  
In Series ◽  
Static Synchronous Series Compensator

<span lang="EN-US">Transient stability in power system is vital to be addressed due to large disturbances that could damage the system such as load changes and voltage increases. This paper presents a multi-machine transient stability using the Static Synchronous Series Compensator (SSSC). SSSC is a device that is connected in series with the power transmission line and produces controllable voltage which contribute to a better performance in the power system stability. As a result, this research has observed a comparison of the synchronization of a three-phase system during single-phase faults before and after installing the SSSC device. In addition, this research investigates the ability of three different types of controllers i.e. Proportional Integral (PI), Proportional Integral Derivation (PID), and Generic controllers to be added to the SSSC improve the transient stability as it cannot operate by itself. This is because the improvement is too small and not able to achieve the desired output. The task presented is to improve the synchronization of the system and time taken for the voltage to stabilize due to the fault. The simulation result shows that the SSSC with an additional controller can improve the stability of a multi-machine power system in a single phase fault.</span>

BIFURCATION IN WIND ENERGY GENERATION SYSTEMS

2010 ◽  
Vol 20 (11) ◽  
pp. 3795-3800 ◽  
Author(s):  
ZHEN LI ◽  
SIU-CHUNG WONG ◽  
CHI K. TSE ◽  
GRACE CHU
Keyword(s):  
Wind Energy ◽  
Bifurcation Analysis ◽  
Single Phase ◽  
Energy Generation ◽  
System Stability ◽  
Generation System ◽  
Constant Power ◽  
Wind Energy Generation ◽  
Constant Power Loads ◽  
Phase Constant

This letter reveals the possibility of Hopf bifurcation in a grid-connected wind energy generation system which handles an unbalanced loading. The wind energy generation system consists of a typical doubly fed induction generator (DFIG) which allows variable speed operation by using partially rated back-to-back quadruple active and reactive power PWM converters. Many control schemes reported in the literature are designed to solve some specific control problems associated with DFIG and have rarely been tested for general stability. Specifically, bifurcation analysis of the system has not been reported so far. We study the system stability in terms of the magnitude of some unwanted oscillation of the voltage link capacitor under a practical scenario where the system interacts indirectly with unbalanced single-phase constant power loads through the power grid. In this letter, the rotor speed of the DFIG is used as a variation parameter for bifurcation analysis. Bifurcation diagram of the voltage link capacitor indicates a Hopf-like bifurcation of the system in super-synchronous operation. This clearly explains the instability phenomenon of the practical DFIG system when unbalanced single-phase constant power loads are connected to the connecting grid.

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